Fuzzy PID control strategy based on piecewise biomechanical model for sit-to-stand movement

Sit-to-stand (STS) motion is the critical initial task in lower limb rehabilitation training exercise of patients with dysfunction. In this paper, based on the dynamic characteristics of the STS motion, a novel piecewise biomechanical function for the STS task modeling is proposed. A Fuzzy PID control strategy based on finite state machine (FSM) is researched for STS motion tracking and STS stability analyzing. Considered the performance of PID controller entirely depending on the adjustment and optimization of the control parameters, a fuzzy controller is used to real-time adjust the parameters to achieve good control effect. The simulation results show that this method has high precision and fast response, and it has certain feasibility.